The present invention relates generally to light beam scanning and imaging systems and methods, and more particularly to a system and a method for ablating a desired shape in a material with a scanning laser beam.
A laser beam imaging system for performing laser ablation generally includes a mask or aperture which is imaged onto the target, typically by an objective lens. For laser eye surgery, the target is the corneal tissue. A field lens may be placed before the mask to alter the characteristics such as the shape of the laser beam at the objective lens in order to reduce the aberration or distortion of the image caused by the objective lens. For example, the laser beam may be partially focused to reduce the diameter of the beam at the objective lens, which in turn will reduce certain types of distortion in the image. The field lens may also be used to focus the laser beam at the focal point of the objective lens to produce an approximately collimated beam emerging from the objective lens onto the target, which can increase the depth of field of the image. To produce a scanning beam, a scanning system is typically placed at or distal of the objective lens. These techniques are typically sensitive to errors in positioning the target along the laser beam path. This sensitivity to positioning errors can produce deviations in the position, size and energy/intensity of a light beam striking a target.
In light of the above, improved systems and methods for delivering a light beam to a target are desirable.